6/20/2023 0 Comments Tidal lockingAs an example, the planet Mercury experiences a 3:2 spin-orbit resonance, meaning it rotates three times on its axis for every two orbits it completes of the Sun. In the past, tidally-locked planets were thought to have extremes climates, thus eliminating any possibility of life. These findings could have significant implications for the study of exoplanets formation and evolution, not to mention habitability. they would be tidally-locked with their star. Furthermore, he found that for the majority, their orbits would be synchronized with their rotation – aka. For example, if Earth formed with no Moon and with an initial ‘day’ that was four days long, one model predicts Earth would be tidally locked to the sun by now.”įrom this, he found that potentially-habitable planets that orbit very late M-type (red dwarf) stars are likely to attain highly-circular orbits about 1 billion years after their formation. And so when you explore that range, what you find is that there’s a possibility for a lot more exoplanets to be tidally locked. “Planetary formation models, however, suggest the initial rotation of a planet could be much larger than several hours, perhaps even several weeks. Weiss/CfAĪs he explained in a University of Washington press statement: Tidally-locked, rocky planets are common around low-mass, M-type (red dwarf) stars, due to their close orbits. What he found was that previous studies had been rather limited and only made allowances for one outcome. He also considered other possibilities, which included slower or faster initial rotation periods as well as variations in planet size and the eccentricity of their orbits. Looking to address this, Barnes chose to address the long-held assumption that only smaller, dimmer stars could host orbiting planets that were tidally locked. However, prior to Barnes’ study, no systematic examinations had ever been conducted. In the past, researchers have used this 12-hour estimation of Earth’s rotation as a model for exoplanet behavior. Astronomers believe this became the case after a Mars-sized object ( Theia) collided with Earth some 4.5 billion years ago.Īside from throwing up debris that would eventually form the Moon, the impact is believed to have struck Earth at such an angle that it gave our planet an initial rotation period of 12 hours. This is why the Moon always presents the same “face” towards Earth, while the side that faces away is known as the “dark side”. In addition to taking 27.32 days to orbit Earth, the Moon also takes 27.32 days to rotate once on its axis. In other words, the orbiting body’s orbital period matches its rotational period, ensuring that the same side of this body is always facing towards the planet or star it orbits.Ĭonsider Earth’s only satellite – the Moon. It occurs as a result of their being no net transfer of angular momentum between an astronomical body and the body it orbits. Credit: Wikipediaįor modern astronomers, tidal-locking is a well-understood phenomena. Tidal locking results in the Moon rotating about its axis in about the same time it takes to orbit the Earth (left side). Also a theorist with the Virtual Planetary Laboratory, his research is focused on the formation and evolution of planets that orbit in and around the “habitable zones” of low-mass stars. The study – which is available online under the title “ Tidal Locking of Habitable Exoplanets” – was led by Rory Barnes, an assistant professor of astronomy and astrobiology at the University of Washington. And according to a new study from the University of Washington, tidally-locked planets may be more common than previously thought. However the question whether or not these planets are tidally-locked, where one face is constantly facing towards their star has been an ongoing one. rocky) in nature, and many were found to orbit within their star’s habitable zone (aka. The majority of these planets have been terrestrial (i.e. In the past few years, astronomers have also detected candidates orbiting the stars Gliese 581, Innes Star, Kepler 42, Gliese 832, Gliese 667, Gliese 3293, and others. These include the discoveries of a rocky planet orbiting the closest star to the Solar System ( Proxima b) and a seven-planet system just 40 light years away ( TRAPPIST-1). Studies of low-mass, ultra-cool and ultra-dim red dwarf stars have turned up a wealth of extra-solar planets lately.
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